<div dir="ltr"><div class="gmail_extra"><br><div class="gmail_quote">On Tue, Feb 16, 2016 at 11:33 PM, Will Senn <span dir="ltr"><<a href="mailto:will.senn@gmail.com" target="_blank">will.senn@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div id=":3er" class="a3s" style="overflow:hidden">* Is there a preferred disk controller/device?<br></div></blockquote><div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif">Hmm hard to say what prefered would mean. I can tell you what history was by what people tended to buy. For the original Unibus PDP-11 implementations, most that had disks used the RK05s because that was what was available. The RL series and RK06/07 come later [Note RK06/07 use a different control - the RK611 and are different technologies in package, recording etc than the RK03/04/5].</div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif">A large number of people used 3rd party/after-market memory & storage, particularly for RT-11 because of cost. There was a thriving business in those days of 3rd party controllers that emulated the DEC ones and could talk to 3d party storage such as the CDC.</div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif">I do not remember the specifics, but I do remember that RL controllers had issues with Unix. I suspect if you look in the driver you may find comments. </div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif">By the time of the QBUS/LSI-11 implementations things started to change. DEC had more storage options, prices on disks had dropped dramatically and IIRC SCSI was beginning to show up. I had stopped doing anything with RT11 by then so I can not tell you what was typical.</div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif">That said, if you used RK05's you certainly would be building a simulated Unibus system that was close to what many people had. </div><br></div><div><br></div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div id=":3er" class="a3s" style="overflow:hidden">
* Is there a controller that supports more disk devices than another (RL vs RK, etc)?<br></div></blockquote><div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif">RK04/5/6 and RP04/5/6 controllers certainly support 8 units.</div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif">My memory is RL can only support 4 (check the bits in the Unix driver - it should be pretty easy to see). Dan Klein and I wrote the original RK611 driver for Unix by hacking on the RP06 driver. My memory is that it supported 8 units also, but we only had 2 on our system.</div><br></div><div><br></div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div id=":3er" class="a3s" style="overflow:hidden">
* Does one device have more capacity than another (either via single disk raw capacity or via overall capacity of attached units)?<br></div></blockquote><div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif">Yes, RP06's were the largest until the SCSI drives show up. But I did not think RT-11 supported them because it's file system would have overflowed. Unix did it by partitioning the physical disk into logical disks. Since Unix could had a uniform namespace, by mounting the logical disk it could piut the back together so the only downside was whatever limit the OS had for the largest file. RT-11 could not do that, so if you partitioned the drive it, you would have DSK C:, DSK D:, DSK E: ...</div><br></div><div><br></div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div id=":3er" class="a3s" style="overflow:hidden">
* Is one device/controller more reliable in SimH than another?<br></div></blockquote><div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif">No idea. </div><br></div><div><br></div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div id=":3er" class="a3s" style="overflow:hidden">
* Do disks need to be formatted before initializing?<br></div></blockquote><div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif">Formatted no, initialized yes.</div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif">Formatting is a low level process that sets up the raw drive, regardless of OS. Its make the physical disk pack recognizable to the physical controller (i.e. turning it in a set of blocks addressed with HD, CYL, SEC). This was usually performed with a standalone program that was part of the disk controller diagnostics.</div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif">Initialization is putting an OS specific file structure on the drive so the logical vector of disk sectors are interpreted as a file system. In older Unix this is mkfs command, in newer versions, newfs.</div><br></div><div><br></div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div id=":3er" class="a3s" style="overflow:hidden">
* Are there some known best practice configurations (so many RL controller, with so many drives, or so many RL and so many RK, etc.)?</div></blockquote><div><br></div><div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">A typical small system install, had 2, maybe 4 RK05 that were dismountable. DEC later created a version of the RK05 that was not dismountable, but could get twice the storage density. A lot of 11/34A's were sold with the configuration.</div> </div></div><br><br></div></div>